Ramberg–Osgood-based stress–strain curve generation using tensile yield/strength for additively manufactured stainless steel

This study presents a quantitative evaluation of the mechanical behavior of additively manufactured stainless steel (AM-SS) produced via the directed energy deposition (DED) process, with a focus on establishing validated constitutive parameters for structural simulations. The true stress–strain response was accurately modeled using a modified Ramberg–Osgood (RO) equation to capture the elastic–plastic transition. Microstructural analysis across the build height revealed a gradient from equiaxed grains at the base to fine cellular–dendritic structures at the top, governed by thermal gradients. Compared to its wrought counterpart, AM-SS exhibited a 64.7% increase in yield strength and a 4.2% improvement in ultimate tensile strength, along with an 8.5% higher elastic modulus, indicating superior mechanical performance. Coefficients of determination (R²) were evaluated to provide statistical validation of results. Fractographic examination confirmed ductile failure with characteristic dimples and voids. The modified RO model showed excellent agreement with experimental results, demonstrating its robustness. This work uniquely bridges the gap in literature by providing experimentally validated material constants for AM-SS, which are critical for accurate finite element modeling and design of AM-based components.